- This paper explores the advantages and disadvantages of implementing a clinical drug trial in a closed community. In the study we conducted a randomized, double-blind, placebo-controlled clinical trial to evaluate the effects of an antacid containing aluminum hydroxide on serum lipoproteins in hypercholesterolemic adults. The results of the trial, which was conducted on two Israeli kibbutzim (rural cooperative communities), have been published previously. The kibbutz presents a unique setting for the conduct of a clinical trial. There were opportunities to uphold inclusion and exclusion criteria carefully, to obtain informed consent, to enhance dietary and drug adherence, to ensure the quality of data collection, to maintain the interest of the participants in the study, and to monitor closely adverse effects and patient safety. This report describes the unique circumstances under which the trial was conducted and the role of the clinician as a clinical investigator and discusses their implications for the internal validity and generalizability of the trial.